Gnorimoschema coquillettella

Gnorimoschema grindeliae

Gnorimoschema baccharisella

Gnorimoschema ericameriae

Gnorimoschema subterranea

... widespread in desert margin, inland foothill, and montane habitats, but [ ] not known in coastal habitats, where it is replaced by a sister species, G. ericameriae ... 

[Gnorimoschema coquillettella causes] gall-like deformities of terminal foliage tips. These are small, ca. 1 cm, onion dome-shaped. hollow 'galls' that appear to consist of leaflets sealed together like the staves of a barrel ... The larva skeletonizes within this shelter, and drops to the ground for pupation, leaving thin, partially eaten leaflets, which wither and dry by midsummer. 

[Fig. 100, pg. 45, is a black-and-white photo of the gall or pseudo-gall]

Larvae cause the growth of soft, variably shaped galls in newly developing stems [, compressing] the stem nodes ... [C]lump[ed] foliage just above [may] includ[e] leaves that form a sheath around the gall.  Later the stem extends beyond this rosette ... By mid- to late March many galls have reached full size (12-20mm long x 10-l2mm diameter) [and] are whitish or pale green with fleshy walls 2-5mm thick ... [L]arvae reach maturity in April, when each cuts a hole in the gall and drops to the ground ... By ... early to rnid-April, [the galls] are white tinged with purplish brown exteriorly. Later, the remaining gall tissue deteriorates [leaving a] clustering of nodes and twigs ... 

[for monochrome photo of gall, see pg. 45]

Gnorimoschema baccharisella Busck

This species is widespread in coastal California, where the larvae cause hard stem galls on Baccharis pilularis (Asteraceae).

Biology.- Gnorimoschema baccharisella is not limited to the immediate coast where the typical, prostrate form of the hostplant occurs. The moth occurs inland, probably throughout the range of the plant, which is widespread in coastal foothill areas, often as an invader in disturbed fields. The original description was based on specimens reared by Koebele probably from Berkeley and Alameda (type locality erroneously cited by Busck as Berkeley County), who found the galls abundant in June. The moth's biology and the parasitoid complex have been studied in detail by Tilden (1951). We have reared the species and/or its parasitoids at several sites and have observed the galls at many others. 

There is a single annual generation. Tilden (1951) reported that eggs are deposited on peripheral branches of the perennial shrubs, and overwintering takes place as eggs. He observed that the newly hatched larva burrows into the tip of the growing terminal. The gall begins to develop at the point of the larval entry, and the hollow gall develops around the larva. Galls develop in the newly elongating stems and are evident by February. They are green, spindle-shaped and reach full size (ca. 18-36mm in length, Fig. 103) by late February or March, but larvae are still quite small and do not survive if galls are removed from the plant before June or July. By this time often are most of them are parasitized. 

At maturity, the larva cuts a hole to the exterior and drops to the ground for pupation, which evidently occurs without diapause. Emergence takes place primarily in August and September. We have collection records of the nocturnal adults from mid-July (Goleta. Sta. Barbara Co.) to late November (Big Creek, Monterey Co.).

This is a strictly coastal species that is evidently specific in larval feeding to Ericameria ericoides ... The larvae of ... G. ericameriae cause gall-like deformities of terminal foliage tips. These are small, ca. l cm, onion dome-shaped. hollow 'galls' that appear to consist of leaflets sealed together like the staves of a barrel, rather than typical growth of gall tissue (Fig. 100 [on pg. 45]). The larva skeletonizes within this shelter, and drops to the ground for pupation, leaving thin, partially eaten leaflets, which wither and dry by midsummer. Adults emerge in July and August

In California, Gnorimoshema sublerraneum is univoltine ... The larvae cause large, nearly spherical to watermelon-shaped galls (17-27mm long, 12-16 mm diameter, Fig. 102) on stems of Asler chilensis [Symphyotrichum chilense] ... Galls are full sized by March or April, but those taken from the plant prior to late April contain immature larvae ... prepupal larvae remain in the galls until pupation in late summer. Typically, galls occurred 12-1 S cm or more above ground level ... When the stems dry in fall, the galls become woody and persist, sometimes for two or more seasons. 

[see pg. 45 for photo]

Gnorimoschemine Moths of Coastal Dune and Scrub Habitats in California (Lepidoptera: Gelechiidae)